The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to ash or etch film on a substrate such as a semiconductor wafer. The substrate processing systems typically include a processing chamber, a gas distribution device and a substrate support. During processing, the substrate is arranged on the substrate support. Different gas mixtures may be introduced into the processing chamber and radio frequency (RF) plasma may be used to activate chemical reactions.
Gas mixtures including fluorine may be used during substrate treatment such as ashing or etching processes. Gas mixtures including fluorine may also be used during cleaning processes for components located within the substrate processing chamber.
During either substrate treatment or chamber cleaning processes, fluorine containing gases (such as sulfur hexafluoride (SF6), nitrogen trifluoride (NF3) or carbon tetrafluoride (CF4) are dissociated. Fluorine ions and radicals react with surfaces of the substrate and/or exposed surfaces in the substrate processing chamber. The fluorine ions and radicals attach to components within the substrate processing chamber. When the substrate processing chamber is subsequently opened and exposed to atmosphere, moisture in the air reacts with the fluorine ions and radicals and creates hydrofluoric (HF) acid.
An ambient air purge process may be used to mitigate the effects of the HF acid that is created when the substrate processing chamber is opened. During this process, the substrate processing chamber is maintained at a constant vacuum pressure and ambient air is introduced. The ambient air contains water, which reacts with fluorine ions and radicals on the components of the processing chamber. The reaction creates gaseous HF, which is then pumped away and treated by a scrubber.